It is known to produce camshafts according to the IHPF process by placing the hollow shaft and mounted thereon components such as cam rings and drive elements according to their function into an IHPF tool. The internal pressure produced causes the shaft to expand and in this way connect the components with the shaft in a force- and form-closing manner (DE 199 09 184 A1; DE 199 32 810A1). The cam rings as well as other components are manufactured with the help of another process and are sized and possess material properties, i.e. wear resistance, conducive to their subsequent application. Drive elements, for example gearwheels, are attached in the same way. By the application of the IHPF process the shaft first undergoes elastic and then plastic deformation which will result in the components to be accurately fixed and secured.
However, caused by the internal pressure also the component to be mounted, for example the cam ring, will undergo an elastic deformation. The elastic deformation of the cam ring spans the manufacturing tolerances existing between the outer contour of the cam ring and the inner contour of the cam profile of the IHPF tool.
This method of adapting the properties of the cam ring only to its subsequent function is associated with the drawback that the permissible deformation of the cam ring may be exceeded and through the formation of an incipient crack breakage or initial damage may be encountered which during subsequent operation will result in a camshaft failure. This will occur if the cam ring has, for example, been incorrectly heat treated. Consequently, it is to be feared that the damage will only occur after the camshaft has been in use in the engine for a longer period of time. The same may be encountered with gearwheels or other drive elements mounted with the aid of the IHPF process. It has also been determined that a higher risk of breakage exists particularly at the cam ring locations where said ring has suffered maximum stresses during the IHPF process, which is the area ahead of and after the cam tip, especially in the radii transitions and at the cam tip.